瑜伽師地論略纂 8.22

8.22

Where the treatise says, "Passing the first watch of the four watches of the night is the early watch of the night," and so forth: In worldly custom in that land, day and night are each divided into four watches, whereas the Buddha-Dharma divides day and night each into three periods, subsuming the four watches into three periods: from beginning to end, passing the first watch is called the first period; from end to beginning, passing the final watch is called the final period; the middle two-and-a-half watches are called the middle period of the night. The day is also like this. Here it accords with worldly custom.